Substrate coating apparatus and semiconductor processing method of improving uniformity of liquid deposition

ABSTRACT

In one aspect, the invention includes a method of improving uniformity of liquid deposition when a liquid is spin-coated over a non-circular substrate. The substrate is retained on a platform and spun. The circular platform includes a plurality of shaping members pivotally connected to the platform. The plurality of shaping members are biased by spinning the platform to form a platform surface with a circular periphery. In another aspect, the invention includes a substrate coating apparatus. Such apparatus comprises a non-circular substrate support configured to support a substrate with a planar surface and non-circular periphery. The apparatus further comprises a motor configured to spin the substrate support. A plurality of shaping members are pivotally connected with the substrate support and each shaping member has a curved outer side surface. Gravity biases the shaping members downward until an angular velocity of the substrate support provides a force to bias each shaping member upward adjacent the substrate to establish a circular surface.

RELATED PATENT DATA

This application is a continuation-in-part of a U.S. patent applicationSer. No. 09/388,855, filed on Sept. 1, 1999 by Express Mail (label no.EL366000052US) entitled “Substrate Coating Apparatus and SemiconductorProcessing Method of Improving Uniformity of Liquid Deposition, listingBrian F. Gordon and Paul D. Shirley as inventors.

TECHNICAL FIELD

This invention relates to methods of improving uniformity of liquiddeposition and to substrate coating. The invention also relates tosubstrate coating apparatuses.

BACKGROUND OF THE INVENTION

In some applications, it can be desirable to form a uniform coating overa non-circular substrate. For instance, it can be desirable to coat auniform layer of photoresist on a square or rectangular shaped radiationpatterning tool, such as, for example, a reticle or mask.

One method of coating a radiation patterning tool is to spin theradiation patterning tool while flowing a liquid thereover. The liquidis commonly applied to the center of the radiation patterning tool andconcentrically spreads outward in radial directions due to the action ofcentrifugal forces during spinning. A difficulty in utilizing theabove-described spin coating method for applying liquid overnon-circular shaped substrates (such as rectangular substrates) is thatthe non-circular periphery of the substrates can cause turbulent airflowduring spinning that affect the uniform flow of the liquid. Theturbulent airflow exerts undesirable aerodynamic forces to the liquid,causing non-uniform flow of the liquid on the substrate. Such can causethe thickness of the liquid to vary across the substrate.

In an exemplary process wherein a liquid photoresist is spun over anon-circular radiation patterning tool, the uneven distribution of theliquid can diminish the accuracy with which the photoresist issubsequently patterned. Such diminished accuracy of photoresistpatterning can in turn lead to diminished accuracy in subsequentpatterning of the radiation patterning tool. It would, therefore, bedesirable to develop improved methods for spin coating non-circularsubstrates.

SUMMARY OF THE INVENTION

In one aspect, the invention includes a method of improving uniformityof liquid deposition when a liquid is spin-coated over a non-circularsubstrate. The substrate is retained on a platform and spun. Thecircular platform includes a plurality of shaping members pivotallyconnected to the platform. The plurality of shaping members are biasedby spinning the platform to form a platform surface with a circularperiphery.

In another aspect, the invention includes a method of coating anon-circular substrate. The substrate is secured to a support and spun.A plurality of shaping members are positioned proximate the non-circularsubstrate to form a circular surface. While spinning, the non-circularsubstrate is coated over with a photoresist material, and then thephotoresist is patterned. After patterning the photoresist, thenon-circular substrate is etched to form a radiation patterning toolwith at least one opening.

In yet another aspect, the invention includes a substrate coatingapparatus. Such apparatus comprises a non-circular substrate supportconfigured to support a substrate with a planar surface and non-circularperiphery. The apparatus further comprises a motor configured to spinthe substrate support. A plurality of shaping members are pivotallyconnected with the substrate support and each shaping member has acurved outer side surface. Gravity biases the shaping members downwarduntil an angular velocity of the substrate support provides a force tobias each shaping member upward adjacent the substrate to establish acircular surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a fragmentary side view of a substrate at one processing stepin accordance with one embodiment of the invention.

FIG. 2 is a elevational side view of a substrate coating apparatus inaccordance with one embodiment of the invention, and shown with the FIG.1 substrate at a processing step subsequent to that shown in FIG. 1.

FIG. 3 is a top plan view of the substrate coating apparatus of FIG. 2with the substrate removed.

FIG. 4 is a view of the substrate coating apparatus of FIG. 3 at aprocessing step subsequent to that shown in FIG. 3.

FIG. 5 is a view of the FIG. 1 substrate at a processing step subsequentto that shown in FIG. 2.

FIG. 6 is a view of the FIG. 1 substrate at a processing step subsequentto that shown in FIG. 5.

FIG. 7 is a view of the FIG. 1 substrate at a processing step subsequentto that shown in FIG. 6.

FIG. 8 is a fragmentary top plan view of the FIG. 1 substrate shown inFIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the Progressof Science and useful Arts” (Article 1, Section 8).

To aid in interpretation of the claims that follow, the terms“semiconductive substrate” and “semiconductor substrate” are defined tomean any construction comprising semiconductive material including, butnot limited to, bulk semiconductor materials such as a semiconductivewafer (either alone or in assemblies comprising other materialsthereon), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductive substrates described above. The term “radiationpatterning tool” is defined to mean any construction used to createradiation patterns for photolithography processing of semiconductivematerials and includes, for example, reticles and masks.

FIGS. 1-8 illustrate a method of improving uniformity of liquiddeposition when a liquid is spin-coated over a non-circular substrate.Referring to FIG. 1, a substrate fragment in process is indicatedgenerally by reference numeral 10. The substrate can be, for example, anon-circular shaped material having a planar surface 11. An exemplarymaterial for the substrate is quartz, as could be utilized forfabrication of a reticle or mask.

Referring to FIG. 2, one embodiment of a substrate coating apparatusencompassed by the present invention is indicated generally by referencenumeral 12. The substrate coating apparatus 12 comprises a shaft 20 anda motor 22 configured to spin a substrate support 14. The substratesupport 14 is configured to secure and support substrate 10 to a supportupper surface 19 adjacent elevated surfaces 43. Elevated surfaces 43 areelevationally above support upper surface 19. In this FIG., substrate 10is shown as a complete substrate (not a substrate fragment as in FIG.1), and therefore, edges 21 of substrate 10 are shown. Substrate coatingapparatus 12 can be configured to provide a vacuum proximate the supportupper surface 19 to secure substrate 10. A plurality of shaping members16 are pivotally connected to substrate 9 support 14 by, for example,hinges 18 (shown in phantom to indicate they are beneath support 19).

In the shown embodiment, support upper surface 19 of substrate support14 has smaller cross-sectional dimensions than substrate 10 to allowedges 21 of substrate 10 to extend beyond support upper surface 19.Accordingly, a grasping apparatus, for example, a pincershaped tool (notshown), can grasp substrate 10 proximate edges 21 to position substrate10 on and off the substrate coating apparatus 12. Alternatively, avacuum wand or other suction apparatus (not shown) may be used to placeand remove substrate 10. Each shaping member 16 comprises upper surfaces25 (shown in FIGS. 3-4), 27, 29 and 31, respectively, a curved outerside surface 17 and a straight inner side surface 23. Additionally, eachupper surface of shaping members 16 defines a lower surface 41elevationally below the upper surfaces (shown only within upper surface29 in this FIG.).

Referring to FIG. 3, shaping members 16 are initially biased downward bygravity with the curved outer side surfaces 17 directed downward. Theshaping members 16 are hinged to a bottom surface of substrate support14. Also attached to the bottom surface of substrate support 14 is shaft20.

Referring to FIG. 4, shaft 20 transfers the rotational energy of motor22 to spin substrate support 14 in direction 24 until an angularvelocity provides a force to bias upwardly each shaping member 16proximate substrate 10 and thereby establish a circular surface 35.Surface 35 comprises upper surfaces 25, 27, 29 and 31 of shaping 11members 16 and elevated surfaces 43. The lower surfaces 41 are coplanarwith support upper surface 19 and together establish a square receivingarea when shaping members 16 are positioned upward.

In one aspect of the invention, a square substrate (not shown) issecured to support upper surface 19. The square substrate has athickness equal to the elevational thickness of surface 35 above supportupper surface 19. When shaping members 16 are biased upward, the squaresubstrate is resting in the square receiving area of substrate support14 and a top surface of the square substrate is coplanar with surface35. Accordingly, the square substrate and substrate support establishone planar surface. In one particular aspect of the invention, thesquare substrate comprises a reticle, and in another aspect a mask.

Alternative methods of positioning shaping members 16 to establishcircular surface 35 could be utilized. Instead of using the spinningaction of substrate support 14 to bias the shaping members 16 upward,shaping members 16 could be releasably locked into the upward positionbefore spinning by, for example, snapping shaping members 16 into placewith substrate support 14. In an additional alternative method, theshaping members 16 could be continually biased upward with, for example,a spring. In this latter example, the shaping members 16 can be forcedto pivot downward by applying a force to surfaces 25, 27, 29 and/or 31.The shaping members 16 spring back into place when released.

An exemplary use of the substrate coating apparatus 12 is to pattern aradiation patterning tool comprising a quartz substrate. Referring toFIG. 5, substrate 10 of FIG. 1 is shown as quartz substrate 10 at aprocessing step subsequent to that shown in FIG. 2 (substrate coatingapparatus 12 is no longer shown). Substrate 10 is shown after a chromecontaining layer 13 and a photoresist material 30 are coated uniformlythereon.

Referring to FIG. 6, photoresist material 30 is converted to a patternedmask. Such can be accomplished, for example, by exposing portions ofphotoresist material 30 to energy, such as, for example, an electronbeam, while leaving other portions unexposed. Subsequently, either theexposed or unexposed portions are removed with a solvent. The patternedmask of photoresist 30 comprises at least one opening 33 in thephotoresist 30. In the shown embodiment, two openings 33 are formed inphotoresist 30.

Referring to FIG. 7, the patterned photoresist material 30 is utilizedas a mask for etching openings 37 into chrome containing layer 13 toform a pattern on the radiation patterning tool. An exemplary thicknessfor the radiation patterning tool is ¼ inch. Moreover, any patterndesign desired in the radiation patterning tool can be formed by varyingthe location and number of openings 37 in chrome containing layer 13.

Referring to FIG. 8, a top view of the radiation patterning tool of FIG.7 is shown with photoresist material 30 removed. Openings 37 are shownhaving a square periphery. However, alternatively, openings 37 couldhave any peripheral shape desired. The line 7—7 of FIG. 8 indicates theline along which the cross-sectional view of FIG. 7 is illustrated.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method of improving uniformity of liquiddeposition when a liquid is spin-coated over a substrate, comprising:providing a substrate on a non-circular platform; and converting thenon-circular platform to a circular platform and retaining the substrateon the circular platform during spinning.
 2. The method of improvinguniformity of liquid deposition of claim 1 wherein the liquid comprisesphotoresist.
 3. The method of improving uniformity of liquid depositionof claim 1 wherein the substrate comprises a radiation patterning tool.4. The method of improving uniformity of liquid deposition of claim 1wherein the substrate comprises a reticle.
 5. The method of improvinguniformity of liquid deposition of claim 1 wherein the substratecomprises quartz.
 6. The method of improving uniformity of liquiddeposition of claim 1 wherein the substrate comprises a semiconductorsubstrate.
 7. The method of improving uniformity of liquid deposition ofclaim 1 wherein the circular platform comprises a plurality of shapingmembers pivotally connected to the non-circular platform, the pluralityof shaping members are biased by spinning the platform to form a surfacewith a circular periphery.
 8. The method of improving uniformity ofliquid deposition of claim 7 wherein the plurality of shaping membersfurther comprise upper and lower surfaces and the non-circular platformcomprises upper and lower surfaces, and wherein spinning thenon-circular platform comprises moving the plurality of shaping membersto provide the lower surfaces in coplanar relation to one another and toreceive the substrate, and the upper surfaces in coplanar relation toone another, to form one surface between the substrate and circularplatform.
 9. The method of improving uniformity of liquid deposition ofclaim 1 wherein the circular platform comprises a plurality of shapingmembers pivotally connected to the non-circular platform and releasablylocked to form a surface with a circular periphery.
 10. The method ofimproving uniformity of liquid deposition of claim 1 wherein thecircular platform comprises a plurality of shaping members pivotallyconnected to the non-circular platform, the plurality of shaping membersare biased to form a surface with a circular periphery.
 11. The methodof improving uniformity of liquid deposition of claim 1 furthercomprising: forming a chrome containing layer over a non-circularsubstrate; performing at least one spin-coating step wherein thespin-coating includes coating over the chrome containing layer with aliquid photoresist material; developing a pattern in the liquidphotoresist material; and utilizing the patterned liquid photoresistmaterial as a mask and etching openings in the chrome containing layerto form a radiation patterning tool.
 12. A method of coating anon-circular substrate comprising: securing a non-circular substrate toa substrate support; spinning the substrate support; positioning aplurality of shaping members proximate the non-circular substrate toform a circular surface; and flowing a liquid coating over the spinningnon-circular substrate.
 13. The method of coating a non-circularsubstrate of claim 12 wherein the plurality of shaping members compriseupper and lower surfaces and the substrate support comprises upper andlower surfaces, and wherein spinning the substrate support comprises thelower surfaces coplanar to receive the non-circular substrate and theupper surfaces coplanar to form one surface between the non-circularsubstrate and substrate support.
 14. The method of coating anon-circular substrate of claim 12 wherein the non-circular substratecomprises a rectangle shape.
 15. The method of coating a non-circularsubstrate of claim 12 wherein the plurality of shaping members arepivotally connected to the substrate support, and wherein the pluralityof shaping members are biased by spinning the substrate support to forma surface with a circular periphery.
 16. The method of coating anon-circular substrate of claim 12 wherein the non-circular substratecomprises a reticle.
 17. The method of coating a non-circular substrateof claim 12 wherein the plurality of shaping members are pivotallyconnected to the platform and releasably locked to form a surface with acircular periphery.
 18. The method of coating a non-circular substrateof claim 12 wherein the plurality of shaping members are pivotallyconnected to the substrate support, the plurality of shaping members arebiased to form a surface with a circular periphery.
 19. The method ofcoating a non-circular substrate of claim 12 further comprising etchingat least one opening over the non-circular substrate to form a radiationpatterning tool.
 20. The method of coating a non-circular substrate ofclaim 12 wherein the non-circular substrate comprises a semiconductorsubstrate.
 21. The method of coating a non-circular substrate of claim12 wherein the non-circular substrate comprises quartz.
 22. The methodof coating a non-circular substrate of claim 12 wherein the liquidcoating comprises photoresist.
 23. A method of coating a non-circularsubstrate comprising: securing a non-circular substrate to a support;spinning the support; positioning a plurality of shaping membersproximate the non-circular substrate to form a circular surface; coatingover the non-circular substrate with a masking material; developing apattern in the masking material; and utilizing the patterned maskingmaterial as a mask and etching at least one opening over thenon-circular substrate to form a radiation patterning tool.
 24. Themethod of coating a non-circular substrate of claim 23 wherein themasking material comprises photoresist material.
 25. The method ofcoating a non-circular substrate of claim 23 wherein the plurality ofshaping members are pivotally connected to the support and biased duringspinning forming a surface with a circular periphery.
 26. The method ofcoating a non-circular substrate of claim 23 wherein the non-circularsubstrate comprises quartz.
 27. The method of coating a non-circularsubstrate of claim 23 wherein the plurality of shaping members arepivotally connected to the support and releasably locked into a positionbefore spinning to form a surface with a circular periphery.
 28. Themethod of coating a non-circular substrate of claim 23 wherein thenon-circular substrate comprises a semiconductor substrate.
 29. Themethod of coating a non-circular substrate of claim 23 wherein thenon-circular substrate comprises a rectangle shape.
 30. The method ofcoating a non-circular substrate of claim 23 wherein the plurality ofshaping members comprise upper and lower surfaces and the supportcomprises upper and lower surfaces, and wherein spinning the supportcomprises the lower surfaces coplanar to receive the non-circularsubstrate and the upper surfaces coplanar to form one surface betweenthe non-circular substrate and support.
 31. A method of improvinguniformity of liquid deposition when a liquid is spin-coated over anon-circular substrate comprising retaining the non-circular substrateon a circular platform during spinning wherein the circular platformcomprises a plurality of shaping members pivotally connected to thecircular platform, and the plurality of shaping members are biased byspinning the circular platform to form a surface with a circularperiphery.
 32. The method of improving uniformity of liquid depositionof claim 31 wherein the plurality of shaping members further compriseupper and lower surfaces and the circular platform comprises upper andlower surfaces, and wherein spinning the circular platform comprises thelower surfaces coplanar to receive the non-circular substrate and theupper surfaces coplanar to form one surface between the non-circularsubstrate and circular platform.
 33. A method of improving uniformity ofliquid deposition when a liquid is spin-coated over a non-circularsubstrate comprising retaining the non-circular substrate on a circularplatform during spinning wherein the circular platform comprises aplurality of shaping members pivotally connected to the circularplatform and releasably locked to form a surface with a circularperiphery.
 34. A method of improving uniformity of liquid depositionwhen a liquid is spin-coated over a non-circular substrate comprisingretaining the non-circular substrate on a circular platform duringspinning wherein the circular platform comprises a plurality of shapingmembers pivotally connected to the circular platform, the plurality ofshaping members are biased to form a surface with a circular periphery.